Acoustic curb



Nov. 12, 1963 J. JENN ETAL 3, 7

ACOUSTIC CURB Filed Jan. 22, 1960 4 Sheets-Sheet 1 E 5 5 bx 5 r 7 r bun/1,0111% EVVENTORS LOUIS JJENN and BY WILLIAM E-MORRISON 96W, wmewwa 52M mm ATTORNEYS N v- 1963 J. JENN ETAL ACOUSTIC CURB 4 Sheets-Sheet 2 Filed Jan. 22, 1960 A TTORNEYS Nov. 12, 1963 J. JENN ETAL 3,110,357

ACOUSTIC CURB Filed Jan. 22, 1960 4 Sheets-Sheet 3 an I: 325

' INVENTOR.

:EI-E- LOUIE J.JENN and BY WILLIAM E.MORRISON KM, WW, 5% a 4mm ATTORNEYS Nov. 12, 1963 J,.JENN ETAL 3,110,357

ACOUSTIC CURB Filed Jan. 22, 1960 4 Sheets-Sheet 4 INVENTOR. LOUIS J.JENN and BY WILLIAM EMORRISON We WW1 5/7MWM ATTORNEYS United States Patent 3,110,357 ACOUSTIC CURB Louis J. Jenn and William E. Morrison, Indianapolis, Ind, assignors to Jenn Air Products Company, Indianapolis, kid, a corporation Filed Jan. 22, 1960, Ser. No. 4,121 1 Claim. (Cl. 181-36) This invention relates generally to a sound attenuator that is designed for use primarily with power air exhausters. More particularly, the invention relates to a prefabricated acoustic curbdesigned to support a centrifugal roof exhauster, the curb being so constructed and arranged as to provide maximum sound attenuation with a minimum internal pressure loss.

In recent years the problem of reducing the sound level of power exhausters has received more and more attention from the industry at large. The reason is readily apparent. There are certain locations such as libraries, schoolrooms, hospitals, conference rooms, churches, auditoriums and the like where a high degree of quietness is desirable if not absolutely necessary. It is, therefore, the primary object of this invention to provide a prefabricated acoustic curb that brings about superior performance in the roof exhauster which it supports, through attenuation of sound and a minimum internal pressure loss.

A further object of the present invention is. to provide for sound attenuation through an entirely difi'ferent approach to the problem than the heretofore conventional one of reducing the revolutions per minute of the units. The conventional approach has resulted in larger and more expensive equipment. It has made it difliculit to provide a low contour design for the modern low parapet buildings. With the present invention, however, the sound attenuation is achieved without having to reduce the r.:p.rn. of the units. It is achieved without sacrificing the strikingly simple lines that are so desired. And it is achieved without changing the low contour design of the exhauster units.

It is a still further object of the present invention to keep the noise level of the exhauster down while keeping the air flow up.

The full nature of the invention will be understood by reference to the accompanying drawings and the following description and claim:

FIG. 1 is a perspective view of the acoustic curb.

FIG. 2 is a vertical section view thereof taken generally along the line 2-2 of FIG. 1.

FIG. 3 is a view similar to that of FIG. 2, but showing the curb in combination with a power roof exhauster shown in side elevation. 7

FIG. 4 is a View similar to FIGS. 2 and 3, but with the roof exhauster shown in partial section and with the curb extending in part below the roof level.

FIG. 5 is a vertical section view of a modified form of the invention with the roof exhauster shown in side elevation.

FIG. 6 is a Vertical section view of a still further mod-iflcation of the invention minus the roof exhauster.

In the drawings the prefabricated acoustic curb which alone and in combination with the roof exhauster comprises the present invention is shown generally 'at 10. The curb is preferably but not necessarily a square metal box 11 having an inturned upper flange 12 and outwardly projecting lower flanges 13. Each of the lower flanges is welded as at 14 to the metal plate or curb bottom 15 that borders the opening 16 of the roof 17 through which the air is. exhausted. The flanges are covered by the usual roofing material 17a.

Carried by the box portion of the curb is a cap 18 that is preferably made out of heavy gauge aluminum. A

3 ,110,357 Patented Nov. 12,1963

round opening 19 is formed through the cap, the opening being defined by the upstanding annular flange 20 and being in vertical alignment with opening 16. The cap is removably connected to the curb through the medium of securing means 21, there being provided a rubber or the like washer 22, on either side of the opening through which the securing means extends to deaden sound. Separating or spacing the cap from the inwardly projecting flanges 12 of the curb is the peripherally extending sound absorbing member 23: which may be formed of sponge rubber or any other material having the desired acoustic characteristics.

Connected to the inner walls of the curb in any satisfactory manner is the acoustically absorbent lining 24. A variety of materials are available for this purpose and any one or more of them may be selected. The same material is also connected to the upper surface of the curb bottom 15, it being understood, of course, that there is an opening in it to receive and accommodate the back draft damper assembly 25 having the louvers 26. The interior surfaces of the box are thus acoustically lined.

Mounted upon and held in place by brackets 27 is a baflle shown generally at 28 that includes a bottom tray or pan 29 that is formed of metal or other substantially hard or solid material. Supported by the pan and connected thereto by the securing means 21] is the sound attenuating member 31.

This member 31 is shown in its preferred embodiment (FIGS. 2 and 3) to consist of a square, substantially flat piece of fibre glass or the like that is suspended axially of the normal air flow path between the inlet opening 16 and the outlet opening 19. It is to be understood, however, that while this type and style of construction achieves maximum sound attenuation, it is nonetheless possible to improve upon the present, conventional exhausters by other constructions.

For example, the baflle need not be square. It need not be so sized (as it is in FIGS. 2 and 3) as to provide an area around its peripheral edges that is at least equal to or greater than the inlet or the outlet area. It need not be so located (as it is in FIGS. 2 and 3) as to close off any direct line of sight between the inlet and outlet.

Furthermore, the baflle need not have the acoustically absorbent material only on its top. Still further, it need not be so located within the box as to provide substantially equal distances between the top of the bafile and the top of the box on the one hand, and the bottom of the baffie and the bottom of the box on the other hand. Still further, the member 31 of the baflle need not be flat as it is shown in its preferred embodiment. instead it may have substantial thickness in its center as compared to the thickness adjacent its peripheral edges.

It is to be understood that while the foregoing alternative constructions can be employed with measurable success, the maximum amount and the highest degree of sound attenuation nonetheless stems from a use of the preferred embodiment shown in FIGS. 2 and 3.

A modification of the invention is illustrated in FIG. 4. This modification is characterized by a box shown generally at that is nested between the joists 117b of the roof 117 in such manner that a portion is below roof lever, as shown. As a consequence of this arrangement the exhauster has an even lower contour.

In view of the requirements of the modification of FIG. 4 the bottom and side walls and 111 respectively of the box are integrally formed, the bottom Wall having the necessary opening 116 for the accommodation of the back draft damper having the louvers 126.

In order to support the box 110 in its nested position the angles are provided. These angles have a base portion that rests upon the roof and over which the roofing material 117a extends. "They also have their upstanding arms connected by securing means 140 to the side Walls of the box. .Carried by the box is the same style of curb cap or cover 118 that has its downwardly extending flanges connected to the box by the securing means 121. V

interposed between the cap and the internal flanges 112 of the box is the sound isolator 123 which may be a flat rubber strip for vibration isolation. Rubber Washers will also preferably be used on either side of the opening through which the cap securing means extends to deaden sound as in the preferred embodiment of FIGS. 2 and 3.

Mounted above the outlet'opening 119 of FIG. 4 and connected to the flange 12b is the rootexhauster that includes among other components the fan 141, the heavy gauge, corrosion-free spun aluminum housing 142 (42 in FIG. 3), the novel U-spring suspension 143 for maximum vibration isolation and the lubricated ball hearing motor 144.

Within the box 110 of this modification is the baffle shown generally at 128, it being the same type as shown in FIGS. 1 and 2, with the metal or the like pan 129 connected by securing means 130 to the brackets 127 and with the pan carrying the sound attenuating member 131. :As will be observed by reference to this figure, the area around the baflie is equal to or greater than the inlet or the outlet area and closes of]? any direct line of sight between the inlet and the outlet. It has accoustically absorbing material such as fibre glass at the top which orally at 228 that includes a bottom tray or pan 229 that is formed of metal or other substantially hard or solid material. Supported by the pan and connected thereto by the securing means 339 is the sound attenuating member 331.

This member 331 is shown in this embodiment to consist of a rectangular substantially flat piece of fibre glass or the like. As shown by FIG. 5, the member obstructs the line of direct vision between the inlet opening 216 and the outlet opening 219. However, it also extends to a point remote from the axis of these openings, i.e., it extends to a point adjacent the right side of the curb in FIG. 5.

is spaced substantially equidistant from the top and from the bottom of the box.

:Still further, the bafile of FIG. 4 is preferably but not necessarily square and flat, and its backing or pan 129 is substantially hard or solid. The box of this figure has its interior surfaces lined with acoustically absorbent material such as fibre glass.

A still further modification of the invention is shown is exhausted. the flanges are covered by the usual roofing material 217a, and the roof is shown supported by the usual joists 21717.

Carried by the box portion of the curb is a cap 213 that is preferably made out of heavy gauge aluminum. A round opening 219 is formed through the cap, the opening being defined by the upstanding flange 22b. The cap is removably connected to the curb through the medium of securing means 221, there being provided a rubber or the like washer 222 on either side of the opening through which the securing means extends to achieve sound deadening results.

Separating or spacing the cap from the inwardly projecting flanges 212 of the curb is the peripherally extending sound absorbing member 223 which may be formed of sponge rubber or any other material having the desired acoustic characteristics.

surface of the curb bottom is provided with an opening to receive and accommodate the back draft damper assembly 225 having the louvers 226. The interior surfaces of the box are thus acoustically lined.

Mounted upon brackets 227 is a baflle shown gen- The width of the member 331 is somewhat less than the width of the rectangular curb 211 so that some air may pass laterally around it from the inlet to the outlet. However, by reason of this construction most of the air will be moved laterally towards the right of the FIG. 5 drawing until it passes around that end of the member 331 whereupon it will move laterally to the left towards the outlet opening through which it will be exhausted. It is also possible, of course, with desirable results, to have the width of member 331 substantially that of the interior width of the box so that all air entering opening 216 will be caused to move laterally to the right until it passes around that end of the member whereupon it moves laterally to the left to the outlet opening through which it is exhausted. Through any of these arrangements the great Proportion of the air that enters the inlet opening is moved laterally after impinging upon the pan that supports the acoustically absorbent material of member 331.

It is to be understood that while member 331 is shown in a substantially flat configuration, it may be provided with substantial thickness in the center just as in the case of the principal embodiment of FIGS. 2 and 3. Similarly as in FIGS. 2 and 3, the battle is readily removable so as to provide a means for access to the damper assembly 225. Also, it is to be observed that the area around baflle 223 is equal to or greater than the inlet or the outlet area. Still further, while the bafile 228 is shown to have the acoustical absorbing materials on the top side only of the pan, it can also have that material on its bottom side as well.

In FIG. 5 the roofing exhauster is shown generally at 242.

A still further modification of the invention is shown in FIG. 6. This modification may be described as the offset type with the inlet 316 offset from the outlet 319.

In the FIG. 6 embodiment of the invention the curb is shown generally at 310, it being of substantially rectangular configuration and having a metal box 311 provided with inturned upper flanges 312 and outwardly projecting lower flanges 313. Each of the lower flanges is welded as at 314 to the metal plate or curb bottom 315 that provides the opening 316 of the roof 317 through which the air 7 is exhausted. The flanges are covered by the usual roofing material 317a.

Carried by the box portion of the curb is a cap 313 that is preferably made out of heavy gauge aluminum. The previously mentioned outlet opening 319 is formed through the cap, this opening being defined by the upstanding annular flange 320. The cap is removably connected to the curb through the medium of securing means 321, there being provided a rubber or the like washer 322 on either side of the opening through which the securing means extends.

Separating or spacing the cap from the inwardly projecting flanges 312 of the curb is the peripheral extending, sound absorbing member 323 which may be formed of sponge rubber or any other material having the desired cushioning characteristics. 7

Connected to all inner walls of the curb in any satisfactory manner is the acoustically absorbent lining 324. A variety of materials are available for this purpose and any one or more of them may be selected.

The back damper assembly in this modification is indicated generally at 325, it having the louvers 326.

It will be noted that this modification is not equipped with a baffle. Nonetheless the air coming through the inlet opening has its direction of flow changed from the vertical direction through the inlet to a horizontal or lateral flow and then to a vertical flow as it is exhausted through the outlet opening. The sound attenuation in this instance comes from the change in direction of the flow of air. Of course, it is possible to mount a baflle of the type heretofore described within this curb for greater sound attenuation results. However, some reduction in the sound level attends this construction, and while not nearly as effective as in the previously described modifications, it is nontheless better sound reductionwise than the present, conventional roof exhausters.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character. The several modifications described herein as well as others which will readily suggest themselves to persons skilled in this art, all are considered to be within the broad scope of the invention, as defined in the appended claim.

The invention claimed is:

An air exhauster for a building having a ventilated roof opening comprising in combination a tubular body having a base wall and a top wall connected by a side wall, said base wall afixed to a building roof, said base wall having an inlet aperture therein registering with a ventilating opening in the building roof, said top wall having a discharge aperture therein, a bafile having a sound attenuating surface mounted within said body to extend transversely thereacross and sized to extend beyond the margin of both said inlet and discharge apertures with its sound attenuating surface facing said discharge aperture, a power driven fan unit mounted in the discharge aperture of said top wall for drawing air through said inlet aperture and around said baflie and out through said discharge aperture, and sound attenuating material covering the inner face of said side and base walls of said body and facing said discharge aperture to absorb the sound of said fan unit flowing from said discharge aperture towards said inlet aperture.

References Cited in the file of this patent UNITED STATES PATENTS 1,289,856 Maxim Dec. 31, 1918 1,948,755 Gnllicksen Feb. 27, 1934 2,176,319 Anderson Oct. 17, 1939 2,576,860 Shapiro Nov. 27, 1951 2,612,831 Lohman Oct. 7, 1952 2,644,389 Dauphinee July 7, 1953 2,750,865 Tutt June 19, 1956 2,823,598 Jenn Feb. 18, 1958 2,875,678 Shepherd Mar. 3, 1959 2,987,983 Solzman June 13, 1961 FOREIGN PATENTS I 357,147 Great Britain Sept. 16, 1931 780,718 Great Britain Aug. 7, 1957 

